A sandwich component should be generally understood as meaning a component that is made up of layers of the same material or different materials. In the simplest case, sandwich components consist of two cover layers, an upper cover layer and a lower cover layer, as well as a core layer, which is arranged between the upper cover layer and the lower cover layer. A connection between the individual layers usually takes place by pressing by means of a suitable tool, such as, for example, a press.
Such sandwich components are used in many different areas. In recent years, however, their importance particularly as a structural component in the area of lightweight automobile construction has increased enormously. A “structural component” is understood here as meaning components of three-dimensional design which do not necessarily have to be load-bearing components of the vehicle. For example, the structural component may also be engine hoods, tailgates or doors.
The prior art discloses many different approaches to the manufacturing of structural components.
For example, a method for manufacturing a sandwich component for use as a structural component of a vehicle is described in DE 10 2012 222 376 A1. This involves first arranging an inner cover layer in a tool, arranging a core layer that is porous at least in certain portions on the inner cover layer and in turn arranging an outer cover layer on said core layer. After the described arrangement of the individual layers, a process pressure is produced against the two cover layers and a core pressure is produced in the core layer to equalize the pressure with respect to the process pressure. In this way, the core layer is not subjected to excessive process pressure and does not have to be over-dimensioned in terms of its stability.
DE 10 2013 013 419 A1 discloses a continuous production method for manufacturing sandwich components that vary on the visible side, an apparatus for manufacturing the sandwich component and a sandwich component that can be manufactured thereby. Starting with a cover layer/core layer/cover layer stack, wherein the cover layers consist of layers of fibrous thermoplastic material, the method presented in this document for manufacturing the sandwich component comprises a first step of heating the sandwich arrangement, wherein the sandwich arrangement is heated until the thermoplastic material of the layer of fibrous material at least begins to flow. The heating takes place in a heating tool, for example a heating press. When the heating press is used, the pressing pressure produced has the effect that the layers of fibrous thermoplastic material adhere to the honeycomb core (core layer). In the next method step, a decorative layer with a foam layer is arranged on the heated sandwich arrangement in such a way that the foam layer faces the cover layer. The viscous thermoplastic of the cover layer brings about adhesive bonding of the foam layer to the sandwich arrangement. After that, the surface of the decorative layer is adapted by means of a form template to the surface structure that the finished sandwich arrangement should have. For this purpose, one or more form template(s) is/are arranged on one or both basic mold surfaces of the compression molding tool. The final step of the method is represented by the cooled compression molding by means of a molding press.
Similarly, EP 1 897 680 A1 describes a method for manufacturing a fiber-reinforced sandwich component with a honeycomb core, wherein the honeycomb core is only closed on one side by means of a cover layer, but the honeycombs of the honeycomb layer are closed on both sides. The method here comprises the steps of: —manufacturing a lay-up comprising the honeycomb core, as well as, at least on one side of the honeycomb core, arranged from the inside to the outside, a curable adhesive layer, a barrier layer and a fiber layer; —confining the lay-up in a gas-tight space; —producing a vacuum in this gas-tight space; —completely or partially curing the adhesive layer between the honeycomb core and the barrier layer under this vacuum such that the honeycomb cells are at least partly evacuated before they are closed by the barrier layer; —after completely or partially curing the adhesive layer, infusing the fiber layer under vacuum with a matrix material, and curing the matrix material under vacuum.